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28 .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/gen/sysconf.3,v 1.8.2.6 2001/12/14 18:33:51 ru Exp $
36 .Nd get configurable system variables
42 .Fn sysconf "int name"
44 This interface is defined by
46 A far more complete interface is available using
51 function provides a method for applications to determine the current
52 value of a configurable system limit or option variable.
55 argument specifies the system variable to be queried.
56 Symbolic constants for each name value are found in the include file
59 The available values are as follows:
62 The maximum bytes of argument to
64 .It Dv _SC_BC_BASE_MAX
65 The maximum ibase/obase values in the
69 The maximum array size in the
72 .It Dv _SC_BC_SCALE_MAX
73 The maximum scale value in the
76 .It Dv _SC_BC_STRING_MAX
77 The maximum string length in the
81 The maximum number of simultaneous processes per user id.
83 The frequency of the statistics clock in ticks per second.
84 .It Dv _SC_COLL_WEIGHTS_MAX
85 The maximum number of weights that can be assigned to any entry of
86 the LC_COLLATE order keyword in the locale definition file.
87 .It Dv _SC_EXPR_NEST_MAX
88 The maximum number of expressions that can be nested within
93 The maximum number of elements in the I/O vector used by
99 .It Dv _SC_JOB_CONTROL
100 Return 1 if job control is available on this system, otherwise \-1.
102 The maximum length in bytes of a text-processing utility's input
104 .It Dv _SC_MESSAGE_PASSING
105 Whether Message Passing option is supported.
106 .It Dv _SC_MQ_OPEN_MAX
107 The maximum number of open message queue descriptors per process.
108 .It Dv _SC_MQ_PRIO_MAX
109 The maximum number of message priorities supported by the implementation.
110 .It Dv _SC_NGROUPS_MAX
111 The maximum number of supplemental groups.
112 .It Dv _SC_NPROCESSORS_CONF
113 The number of processors configured.
114 .It Dv _SC_NPROCESSORS_ONLN
115 The number of processors online.
117 The maximum number of open files per user id.
119 The size of a system page in bytes.
120 .It Dv _SC_RE_DUP_MAX
121 The maximum number of repeated occurrences of a regular expression
122 permitted when using interval notation.
124 Return 1 if the system supports regular expression handling.
126 Return 1 if saved set-group and saved set-user ID is available,
129 Return 1 if the system supports the
132 .It Dv _SC_STREAM_MAX
133 The minimum maximum number of streams that a process may have open
135 .It Dv _SC_TZNAME_MAX
136 The minimum maximum number of types supported for the name of a
141 with which the system
144 Return 1 if the system supports the
146 Shared Memory Feature
147 for both compilation and execution, or 0 if only compilation support is
150 Return 1 if the system's C-language development facilities support the
151 C-Language Bindings Option, otherwise \-1.
153 Return 1 if the system supports the C-Language Development Utilities Option,
155 .It Dv _SC_2_CHAR_TERM
156 Return 1 if the system supports at least one terminal type capable of
157 all operations described in
160 .It Dv _SC_2_FORT_DEV
161 Return 1 if the system supports the FORTRAN Development Utilities Option,
163 .It Dv _SC_2_FORT_RUN
164 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
166 .It Dv _SC_2_LOCALEDEF
167 Return 1 if the system supports the creation of locales, otherwise \-1.
169 Return 1 if the system supports the Software Development Utilities Option,
172 Return 1 if the system supports the User Portability Utilities Option,
177 with which the system attempts to comply.
182 is not successful, \-1 is returned and
184 is set appropriately.
185 Otherwise, if the variable is associated with functionality that is not
186 supported, \-1 is returned and
189 Otherwise, the current variable value is returned.
193 function may fail and set
195 for any of the errors specified for the library function
197 In addition, the following error may be reported:
207 Except for the fact that values returned by
209 may change over the lifetime of the calling process,
210 this function conforms to
213 _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are nonstandard, but implemented
218 function first appeared in
221 The value for _SC_STREAM_MAX is a minimum maximum, and required to be
222 the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously
223 small and misleading number.